IronKey reckons it has made its super-secure S100 crypto USB drive family even harder to crack.

The biggest enhancement of the new S200 model is probably physical, with a revised steel case that has no seams, making it nearly impossible, the company claims, to prize open without damaging the crypto chip inside.

It is this tamper-proofing modification which has gained the drive its much-coveted FIPS-140-2 Level 3 validation, although the claim that it is the only drive to have reached this level could reflect the speed at which certification take place for rival drives rather than any design inferiority.

The crypto chip inside the drive is a second generation proprietary design that features AES 256-bit key length compared to the old S100 model's 128 bits, and also uses cipher block chaining (CBC) for added theoretical key protection.

The new chip improves encryption-decryption performance slightly, the company says, especially when coping with smaller files.

Subtle enhancements have also been made such as a small printed barcode on the end of each drive, which corresponds to the internal identification of a drive. This makes asset tracking easier to verify. Mac users will be pleased to hear that the drives now support the Silver Bullet remote wipe feature.

It is worth mentioning that the company has in recent months been handing out drives that have the physical case design of the S200 but without the internal hardware enhancements. According to a company spokesman, because the new S200 will only be made available from August, any user who has a case without the seams and with two holes in the end of the drive must have one of these units.

The rest of the feature set remains as it was before which covers integrated anti-malware, autorun control, lockdown of the drive when plugged into non-trusted PCs, and extensive management and key recovery features in appropriate models.

"FIPS 140-2, Level 3 is most often associated with devices such as high-confidence security hardware typically found in the data centre," said Scott Crawford of Enterprise Management Associates in IronKey's press materials. "To have implemented this in a USB form factor is a noteworthy achievement."

As with its predecessor, the S200 will sell drive comes in three versions, Basic, Personal and Enterprise. Pricing was not made available by IronKey but should be comparable to the current model.